1. Field of the Invention
The present invention relates to an auto-ignition support system and method for internal combustion engines including heterogeneous-charge, compression-ignition four-cycle engines and homogeneous-charge compression-ignition four-cycle engines.
2. Description of the Background Art
It is known practice to design four-stroke cycle internal combustion engines to accommodate auto-ignition (or compression-ignition) combustion. It is proposed to control auto-ignition timing by changing the temperature of fresh charge of air and fuel mixture by heating the intake air. It is also proposed by JP-A 11-343874 to use heat energy of a portion of residual gas escaped from cylinder in the power stroke of one engine cycle to heat fresh charge of the subsequent engine cycle.
Although it is possible to control auto-ignition timing by heating fresh charge using the heat energy of residual gas of the preceding engine cycle, a need remains for improvement of system and method for auto-ignition support for practical application to internal combustion engines.
An object of the present invention is to provide auto-ignition support system and method for four-stroke cycle internal combustion engines to meet the above-mentioned need.
According to one aspect of the present invention, there is provided an auto-ignition support system for an internal combustion engine including a cylinder including at least one intake valve which is selectively open to allow at least air to enter the cylinder and at least one exhaust valve which is selectively open to allow residual gas escape from the cylinder after a firing event, the system comprising:
a device communicably coupled with the cylinder, effective to allow an amount of gas to enter the cylinder in the compression stroke of an engine cycle after valve closure of the intake valve, said gas being higher in temperature than the air that is allowed to enter the cylinder when the intake valve is open.
According to another aspect of the present invention, there is provided an auto-ignition support system for an internal combustion engine including a cylinder including at least one intake valve which is selectively open to allow at least air to enter the cylinder and at least one exhaust valve which is selectively open to allow residual gas escape from the cylinder after a firing event, the system comprising:
a gas trap including a trap valve, and a trap chamber selectively communicable with the cylinder through a port when said trap valve is open; and
a valve actuator which selectively actuates said trap valve,
said valve actuator being effective to selectively open said trap valve to allow escape of a portion of residual gas from the cylinder to said trap chamber in the power stroke of one engine cycle before valve opening angle of the exhaust valve and to trap said portion of residual gas escaped from the cylinder,
said valve actuator being further effective to selectively open said trap valve to allow said trapped portion of residual gas to enter the cylinder in the compression stroke of the subsequent engine cycle after valve closure of the intake valve.
According to still another aspect of the present invention, there is provided an auto-ignition support method for an internal combustion engine including a cylinder including at least one intake valve which is selectively open to allow at least air to enter the cylinder and at least one exhaust valve which is selectively open to allow residual gas escape from the cylinder after a firing event, the method comprising:
for one engine cycle, allowing escape of a portion of residual gas from the cylinder during the power stroke before the exhaust valve is open;
trapping said portion of residual gas escaped from the cylinder; and
for the subsequent engine cycle, allowing said trapped portion of residual gas to enter the cylinder in the compression stroke after valve closure of the intake valve.